Electric brake device

Abstract

An electric brake device includes a brake pad, an axial force sensor and a controller. The brake pad is pressed against a rotation face of a brake rotor in a direction perpendicular to the rotation face. The axial force sensor detects a pressure of the brake pad. The controller performs a speed reduction control which is an operation target, based on at least one of the pressure of the brake pad and a reduced speed obtained from a wheel speed sensor.

What is claimed is: 
     
       1. An electric brake device, comprising:
 a brake pad configured to apply a pressure against a rotation face of a brake rotor in a direction perpendicular to the rotation face; 
 a linear converter configured to convert a driving force of a motor into a linear movement to transmit the linear movement to the brake pad; 
 an axial force sensor, provided at the linear converter, and configured to detect a brake axial force obtained by the pressure by the brake pad; and 
 a controller configured to perform a speed reduction control which is an operation target, and configured to obtain a speed from a wheel speed sensor; 
 wherein the controller is configured to perform the speed reduction control based on the brake axial force in a case where the speed is higher than zero and lower than a predetermined speed, and to perform the speed reduction control based on the speed obtained from the wheel speed sensor in a case where the speed is higher than or equal to the predetermined speed. 
 
     
     
       2. The electric brake device as set forth in  claim 1 , further comprising:
 a mechanical holding mechanism configured to mechanically keep the pressure of the brake pad, in a case where neither the axial force sensor nor the wheel speed sensor output values in a predetermined time period. 
 
     
     
       3. The electric brake device as set forth in  claim 1 , further comprising:
 a self-servomechanism configured to increase an axial force in a direction in which the brake pad applies the pressure, with accompanying a rotation of the brake pad, when the brake pad applies the pressure against the brake rotor. 
 
     
     
       4. A method for controlling an electric brake device, comprising:
 applying a pressure by a brake pad against a rotation face of a brake rotor in a direction perpendicular to the rotation face via a linear converter configured to convert a driving force of a motor into a linear movement to transmit the linear movement to the brake pad; 
 detecting a brake axial force obtained by the pressure by the brake pad by an axial force sensor provided at the linear converter; 
 obtaining a speed from a wheel speed sensor; 
 determining whether the speed is lower than a predetermined speed; 
 performing a speed reduction control which is an operation target, based on the brake axial force in a case where the speed is higher than zero and lower than the predetermined speed; and 
 performing the speed reduction control based on the speed in a case where the speed is higher than or equal to the predetermined speed. 
 
     
     
       5. The method as set forth in  claim 4 , further comprising:
 mechanically keeping the pressure of the brake pad, in a case where neither the axial force sensor nor the wheel speed sensor output values in a predetermined time period.